Hard alloys



Patented Oct. 27, 1936 UNITED STATES PATENT OFFICE HARD ALLOYS ElectricCompany, Schenectady,

N. Y., a corporation of New York 7 No Drawing.

a No. 529,898.

3 Claims.

This invention relates to hard metallic alloys for implements and tools.

It has been known for a long time that elementary boron has a hardnessapproaching that 5 of diamond. It has, therefore, often been at-.tempted to use boron as a material for tools and implements of all kindsin which great hardness is required. However pure boron when it has beenmelted, but especially in the sintered condition, is so brittle thathitherto it has not been possible to make use of it in practice. Peoplehave, therefore, confined themselves to using boron only as a materialto be added to other metals and metal alloys for increasing thehardness.

The invention rests upon the discovery that the great brittleness ofboron can be avoided While its hardness is maintained practicallyunaltered if one or more metals or metal alloys, the melting point ofwhich lies above 1000 C., are added to the boron as additionalmaterials, that is to say the boron remains the foundation materialproper. Those metals which easily enter into compounds with boron, suchfor example as titanium, zirconium, vanadium, chromium, tungsten,manganese, cobalt and iron, have proved particularly suitable asadditions.

The shaping of the parts or tools made from the new alloy can beefiected by casting the alloy as a liquid into a mould or by pressingand sintering a pulverulent starting mixture, in some cases by hotpressing. The melting or sintering or hot pressing is preferablyeffected in a neutral atmosphere, for example in argon 5 or hydrogen oreven in vacuum. For the production of particularly dense products it hasbeen found to be advantageous to deprive the powder mixture or gasesascompletely as possible by thorough heating in a vacuum furnace.

Application April 13, 1931, Serial In Germany July 8, 1930 In order thatthe invention may be clearly understood and readily carried into effect,one method of making an alloy in accordance therewith will now bedescribed by way of example.

Pure boron of as fine a grain as possible is intimately mixed with about15% of zirconium, also in powder form, and heated in vacuum at about1350 C. until gases are no longer given off. The mixture is then pressedin a press mould to a body of the desired dimensions and is finallypreliminarily sintered in vacuum at about 1800 C. As a result thepressed body acquires such a strength and density that it can be workedand brought to the desired final shape. It is then finally sintered atabout 2100 C., also in vacuum. During the preliminary sintering andfinal sintering it is preferable that the gases set free by the heatingshould be continuously drawn off. If the stated conditions are adheredto the finished product is dense and combines the high hardness of boronwith a strength and toughness sufiicient for practical use.

What I claim and desire to secure by Letters Patent is:-

l. A hard metallic alloy composed of about 15% of zirconium and about ofboron.

2. A hard metallic alloy composed of about 15% of one or more metalsselected from the group consisting of titanium, zirconium, vanadium,chromium, tungsten, manganese, cobalt, and iron; the remainder boron.

3. A hard metallic alloy composed of about 15% of an element selectedfrom the group consisting of titanium and zirconium, and about 85% ofboron.

' KARL scnRo'rER.

KURT MOERS.

